1. Technical Field
The present invention relates to multi-moduled nanoparticle-structured sensor arrays on flexible substrates. The invention further relates to methods for fabricating nanoparticle-structured sensor arrays on flexible substrates. The invention also relates to methods for chemical and biological sensing using flexible thin-film based sensors.
2. Description of Related Art
Organic monolayer-capped metal nanoparticles can be used as chemical sensing nanomaterials for chemiresistor and piezoelectric sensors on rigid substrates. In particular, molecularly-mediated thin film assemblies (TFA) of nanoparticles via covalent bonding or hydrogen-bonding of mediator (or linking) molecules can be used to construct chemiresistive sensing arrays on rigid glass substrates. The combination of the organic monolayer shells, the nanocrystal cores, and the molecular linkers for constructing sensing array materials enables the ability to tune the composition, functionality, and interparticle spatial properties of the sensor for enhancing sensitivity, selectivity, detection limit and response time. In employing nanostructured thin film materials for the design of chemiresistive sensing arrays, one can use the correlation between the electrical conductivity and the nanostructural parameters including particle size, interparticle distance, and dielectric constant of the interparticle medium. These parameters determine the activation energy in a thermally-activated conduction path, and thus have an impact on the electrical signal amplification in sensing applications. Recently, sensor devices have begun to be fabricated on flexible, e.g., organic light-emitting diodes. In comparison with conventional silicon, glass or ceramic technology, some of the advantages of flexible sensor devices include simplified processing, low-cost manufacturing, and increased flexibility for their integration in wraps, lightweight electronics packaging platform, and conformal adaptability in various complex or special sensing environment.
Currently, a variety of transducers are available commercially or in research labs to detect volatile organic compounds (VOCs), chemical warfare or toxic agents, e.g., ion mobility spectrometers, surface acoustic devices, mass spectrometers, antibody-based technology with optical reporters, gas chromatography and mass spectroscopy, fluorescence-based sensor array, etc. The sensitivity, selectivity and response speed of some systems, are however limited, especially in monitoring applications. Most commercial gas sensors use semiconductor materials (e.g., SnO2) due to their high sensitivity and simple electronics. The main drawbacks include the lack of selectivity, poor long-term stability, and high temperature requirement.
There is therefore a need in the art for chemiresistor sensors comprising nanoparticle-structured sensing materials on microelectrodes patterned on flexible substrates. There is also a need in the art for chemiresistor sensors that are more selective and stable and that require lower temperatures to operate than existing sensors. There is also a need in the art for methods of fabricating sensors that lower fabrication costs for individual sensors, by reducing the cost of integrating the array onto a single substrate, and by eliminating the sensor-to-processor attach cost. There is also a need in the art for methods for cost-effectively fabricating large-area and high-performance flexible sensor devices.
Citation or identification of any reference in this application shall not be considered an admission that such reference is available as prior art to the present invention.